Development And Test Investigation On A New-Style Washer For Vegetables

Vegetable cleaning is the essential work procedure to vegetable processing and cleaned vegetable production. At present, Vegetable cleaning mainly depends on handwork in China. Its work efficiency is low and cleaned vegetable is dispersive. These actuality make against vegetable industrialization. The existing washer of vegetable is prone to damage the leaf-vegetable and is unfit for leaf-vegetable cleaning. Therefore, A new-style washer of vegetable was developed. The machine's washing force is ultrasonic and air bubble. When the washer is used to clean vegetable, the contamination of vegetable surface is clear away effectively and the bacterium is killed to a certain extent and the vegetable organizational structure (including leaf-vegetable) isn't damaged.The mechanism of using ultrasound and air bubble to clean vegetable is analysed:(1) ultrasound's steady cavitation, instantaneous cavitation, micro-streaming, micro-jet and self-high-frequency oscillation can wipe off effectively the contamination of vegetable surface.(2)the infectant of vegetable surface can be cleaned out effectively by cavitation erosion which produced when air bubbles collapse and complex turbulence (water's welter and burble )which caused by air flow.The vegetable cleaning tester which washing force is ultrasound and air bubble is developed. The orthogonal test of vegetable cleaning was done in this tester and the optimum parameter of vegetable cleaning was discovered: the ultrasonic power is 450W, the air bubble's intensity is 25m3 /h and the cleaning time is 4minutes. The washer of vegetable was developed on the basis of the optimum parameter. The productivity of this washer of vegetable is 100~300kg per hour. When the washer is used to clean vegetable, the vegetable's abluent ratio is over 95% and vegetable's organizational structure(including leaf-vegetable) isn't damaged.The mechanism of ultrasonic to kill bacteria is discussed in theory. Ultrasound cavitation phenomena is produced when ultrasonic propagates in liquid medium. The phenomena causes a series of physical effects such as high temperature, high pressure andelectromagnetic radiation. These effects can destroy the bacterial organization structure and kill them accordingly. The greengrocery was cleaned by ultrasonic of 450W for 2 minutes, the killing rates is 30.0% to greengrocery's bacterium. The killing rates of Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus were exposure to ultrasonic of 600W for 5 minutes were 28.4%,31.5% and 20.4%.